Spool for photographic developing tanks



Oct. 11, 1949. J, c. eRoVER, JR

SPOOL FOR PHOTOGRAPHIC DEVELOPING TANKS Filed Feb. 21, 1946 2Sheets-Sheet 1 I Filed Feb. 21. 1946 Oct. 11, 1949. J, c, GROVER, Jiq2,484,341

SPOOL FOR PHOTOGRAPHIC DEVELOPING TANKS 2 Sheets-Sheet 2 Patented Oct.11, 1949 UNITED STATES ATENT OFFICE SPOOL FOR PHOTOGRAPHIC DEVELOPINGTANKS trustee Application February 21, 1946, Serial No. 649,336

4 Claims. 1

My invention pertains to developing tanks suitable for use in thedeveloping of cut or roll photographic film and has as a primaryobjective the provision of a simple, inexpensive tank of the typedescribed which may be used to develop substantially any type of filmcommonly encountered.

Further objectives are to provide a daylight film developing tank whichcan be inexpensively built to provide means for positively insertingfilm into the developing spool, and to provide for adequate circulationof developing fluids even when the tank is loaded with film to itsmaximum capacity.

These and other objects Will become apparent from the followingspecification and from the drawings in which Figure 1 is a partiallysectioned elevation of one form of my invention;

Figure 2 is a horizontal section taken along the line 2-2;

Figure 3 is an end view of one of the spool end members;

Figure l is a perspective view of an end member detent;

Figure 5 is a partially sectioned elevation of another modification ofthe spool;

Figure 6 is a sectional view taken along the line 6-4); and

Figure '7 is a perspective view of a film clip.

Developing tanks of the type available today are generally classifiableinto two general categories, namely, those adapted for the developmentof cut film and those adapted for the developing of roll film. While insome instances tinterchangeable spools are provided, there is no singlespool for a developing tank available on the market today which willsatisfactorily develop either roll or cut film.

In the roll film type of developing tanks, diificulty is oftenexperienced in obtaining a rapid and thorough circulation of thedeveloping fluid which often results in a cloudy, distorted, orimproperly developed negative. Many of the prior art devices, in orderhave reduced the amount of film which could reasonably be placed in adeveloping spool in order to insure better circulation. I have found,however, that this is unnecessary as my spool means will develop eitherroll or cut film and at 4 the same time obtain adequate circulation ofthe developing fluid, regardless of the greatly increased density ofloading by proper design of the film-receiving grooves formed in the endmembers of the spool.

to eliminate this diificulty,

Referring to Figure 1, I provide a container preferably having anintegral bottom and. provided with a peripheral flange ll around itslip. A cover l2 having a grooved periphery I3 is shaped to fit over theperipheral container flange i l in such manner as to exclude light. Thecentral portion of the cover 12 may be dished inwardly and provided witha centrally disposed opening It to admit developing fluid. The inner aceof the cover l2 has a central downwardly e.- iding tubular boss l6adapted to receive one end of a spool core [1. The inner surface of thebottom of the container in is provided with a similar boss It to insurevertical alignment of the developing spool.

The core '3' is preferabl of generally tubular shape and has formed onthe external surface an axially disposed external groove 2! extendingpartially through the wall. The base of the groove 2! has formed thereina series of cross grooves 22 normal to the axis of the core I! andextending across the base of the axial groove 2|. The interval betweenthe grooves 22 is indicated by numbers embossed on the core adjacent thegroove indicating thereby the type of film adapted to be received by thespool when set at the interval indicated. The lower end of the core Ilmay be provided with a series of notches or serrations 253 to facilitatethe discharge of developing liquid entering through the hollow centralsection of the core. In operation the bosses l8 and 18 extend inwardlybeyond the notches it to exclude light. A tube it may be provided toextend through the opening I in the cover I?! and is slit at one end toengage a cross pin 25 extending diametrically across the core lladjacent its lower end to permit rotation of the spool duringdeveloping, the opening in the tube being suificiently large to permitthe insertion of a thermometer. A pair of end members, generallydesignated 2d, are-provided, each having similar surfaces. The diameterof the end members is such that they will fit loosely within thecontainer l0 without binding and allow adequate space for the freemovement of developing fluid between the edges of the end members 25 andthe inner wall of the container ill. Each of the end members 24 isprovided with a centrally disposed boss 26 through which extends anopening 2i having a diameter slightly larger than the external diameterof the core 1?. The upper and lower surfaces of the boss 25 arepreferably recessed to receive spring detents 28 which in assembly arealigned with the axial groove 2! and positioned to properly indexthe endmembers 24 with respect to each other. The detent members 28 are formedof spring stock having a width less than the width of the groove 2| andadapted to clip over the boss 25 extending through the opening 21. Eachof the detents 28 is provided with a centrally disposed projection 29which, When properly assembled, will extend into the groove 2| andresiliently engage the grooves 22 thereby removably maintaining the endmembers 24 at the desired position on the core I! in a manner well knownto the art.

One surface of each of the end members 24 is provided with a low pitchspiral groove 3| to receive roll film. For convenience, the externaledge of the end member 24 is provided with an outwardly extending nib 32adjacent the opening into the spiral groove 3| to assist in guiding thefilm into the spiral. Nib 32 has a rounded outer edge to enable one toidentify the starting point of the low pitch groove by the sense oftouch. The other surface of each of the end members is provided with aplurality of high pitch spiral grooves 33 of the type adapted to receivecut film. The openings to these spirals are similarly provided with nibs32. A square-edged nib 35 adjacent each of the high pitch grooves 33aids in identifying these grooves and assists in guiding the fiim intothe spiral.

The operator in preparing my improved developing spool for use willtherefore determine the type of film to be developed. If cut film is tobe employed, the end members of the spool are assembled with the faceshaving the high pitch spiral grooves 33 facing each other and spacedapart a distance equal to the width of the film 3:;

being developed. The film may then be inserted in the grooves 33, thespool inserted in the container It, the cover l2 placed on thecontainer, developing fluid admitted through the opening l4.

If on th other hand roll film is to be developed, the end members willbe assembled on the core with the faces of the end members containingthe low pitch spiral groove 3| facing each other and spaced apart adistance approximately equal to the width of the film. The roll film maythen e inserted in the groove 3| and developed in like manner. The samespool may therefore be used for either cut or roll film of substantiallyany width, provided the width does not exceed the capacity of the spool.

A modified form of my invention is illustrated in Figures 5 and 6 inwhich reversal of the end members 24 is not necessary. In thismodification of my invention the adjacent surfaces of the end members 24are provided, as previously described, with a low pitch spiral groove 3ihaving a nib 32 formed adjacent the entrance to the groove. However, inthis modification there is superimposed over the low pitch spiral 3| oneor more high pitch spiral grooves 34 preferably hav ing a depth slightlygreater than the depth of the low pitch spiral groove 3| and adapted toreceive cut film.

At the juncture of grooves 3| and 34 the ends of the solid section orlands 36 formed in the face of the end member 24 by cutting the groove3| are beveled as at 31 to permit roll film to be inserted in the groove3| and across the groove .54 without difiiculty. The end members 24 inthis modification are, as in the previously described form, movable withrespect to each other and except for the described differences, similarin structure.

It may be seen that the necessity for reversing the end members has beeneliminated in this modification since by spacing the end members 24 theproper distance apart, either cut or roll film may be inserted in thesuitable grooves. It is not essential that the groove 34 be deeper thanthe groove 3|, however, I prefer to employ the structure described sincethe deeper groove 34 serves as a developing liquid distributing channelwhen roll film is inserted.

The outer edge of the end members 24 is notched at 39 adjacent thegroove entrance to receive spring clips 4|. The clips 4| are providedwith a tongue 42 extending downwardly into the low pitch spiral groove3| and only partially filling the groove. The other end of the clip 4|may be riveted or otherwise secured to the bottom of the end member 24or formed with a hook 43 shaped to receive a flange 44 which may beformed on the opposite surface of the end member. The clip 4| is turnedoutwardly away from the edge of the end member 25; to permit the tongue42 to be forced inwardly by the application of pressure to the clip ll adistance suificient to bring the tongue 42 in contact with the oppositeside of the groove 3 The purpose of these clips is to act as vises orjaws to assist in the insertion of roll film in the assembled spool.

Since the width of the groove 2| is greater than the width of the springdetent 28, a certain .5 amount of relative movement about the axis ofthe core ll is permitted. If the roll film should become difiicult toinsert, the clip 4| on either end member may be depressed by one thumbthereby gripping one edge of the film. If pressure is not applied to theclip on the other end member, the end members may be rotated by thehands in opposite directions thereby forcing the film a short distanceinto the groove 3|. Pressure may then be released on the one clip 4| andapplied to the other clip 4|, repeating the process, but rotating theend members in opposite directions thereby gradually working the filminto the spool. Since the groove 3| is relatively narrow, there islittle chance of the film buckling unless a major obstruction occurs inthe path of the film.

I do not wish to limit myself to the precise form of clip shown sincethere are many possible variations; for example, a wedge-shaped or othersuitable beveled member may be pivotally or resiliently supported abovethe groove in a normally I, a with the exception of the 28, can beformed by pressing or inoperative position, and when depressed by thethumb, project into the groove, wedging the film between the clip andthe Wall of the groove. While I may provide a similar pair of clips foreach of the cut film grooves, the need for them is less likely to arise.

The parts of my device may be formed of any material that is resistantto the action of developing liquids to which it will be subjected. Hardrubber constitutes a suitable material as do many thermosetting andthermoplastic materials currently available. A high degree of economy iseffected in manufacture since all of the parts, clips 4| and the detentmolding and the metal members can be rapidly formed on automatic formingmachines such as punch presses.

In accordance with the requirements of R. S. 4888, I have hereindescribed a preferred form of my invention but I do not wish to bespecifically limited to the precise materials or details hereindescribed except in so far as specifically incorporated in the appendedclaims.

I claim:

1. A developing spool comprising a pair of end members having alignedopenings, a core extending through said openings, and means forpositioning the end members on the core a predetermined distance apart,each of the end members having a low pitch spiral groove to receive rollfilm and a plurality of high pitch spiral grooves to receive cut filmwhereby either type of film may be supported for developing by the samespool.

2. An end member for use in a developing spool, said end member having asingle low pitch spiral groove to receive roll film and a, plurality ofhigh pitch spiral grooves to receive cut film.

3. An end member for use in a developing spool,

said end member having a single low pitch spiral groove formed in oneface thereof and a plurality of high pitch spiral grooves formed in theother face thereof.

4. A developing spool comprising a core, end members on the core, eachof said end members having a high pitch and a low pitch spiral grooveformed therein, means for maintaining the end members a predetermineddistance apart on the core, said means providing relative rotation ofsaid end members, and clip means on each of the end members, a portionof each clip being adapted to extend into low pitch spiral groove and,in response to pressure on the clip, wedge a film strip between a wallof said low pitch groove and said clip whereby the film strip may bedriven into the spool by alternately rotating the end members andactuating the said clip means.

JOHN C. GROVER, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date H 1,191,166 Elliot et a1 July 18,1916 2,956,298 Schnelz Oct. 6, 1936 2,151,997 Fink Mar. 28, 19392,243,453 Busse May 27, 1941 2,297,525 Anheuser Sept. 29, 1942 202,298,963 Naylor Oct. 13, 1942 2,325,823 Wilson Aug. 3, 1943 2,344,998Morgan Mar. 28, 1944 FOREIGN PATENTS 25 Number Country Date 634,464Germany Aug. 27, 1936

